Abstract
Minoridai, Matudo, Tiba High temperature gas reactor's (HTGR) can produce high temperature gas. The graphites will be used as an important structural material for the HTGR, but they may be subjected to oxidation under practical use. In the present study, accelerated oxidation experiments were carried out for an isotropic graphite (IG-11) and a fine-grained isotropic graphite (IG-110) under various stresses to examine effect of stresses on the oxidation. As a result, both of the isotropic and fine-grained isotropic graphites were found to deteriorate by the oxidation. In particular, the oxidation was accelerated under tensile stress. On the other hand, compressive stress restrains the oxidation. The microstructures of the specimens were observed by means of SEM and an optical microscope. In each case, the occurrence of various kinds of micropores, which may affect mechanical properties and so forth, are found.
